Telephone system



Dec. 22, 1942. LOGAN 2,306,173

TELEPHONE SYSTEM Filed June 12, 1940 lNl EN TOR M A. LOGAN MWWIW Patented Dec. 22, 1942 NiTED STATES Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application June 12, 1940, Serial No. 240,072 I 7 Claims. (01. 17 9-8.5)

This invention relates to telephone systems and particularly to arrangements in systems for identifying subscribers of party lines,

An object is to obtain increased eihciency in the use of identification tests for determining the calling subscribers on party lines.

Heretofore arrangements of this kind have been used in which tests were performed by having three-element space discharge devices at the subscribers stations on a party line for identifying calling parties. In such cases when a subscriber calls, a current of a particular polarity is applied to operate a space discharge device, and cause it to unbalance relay devices at the central oflice to identify the calling party.

Another arrangement has been proposed in my copending application, Serial No. 316,902, filed FebruaryZ, 1940, which makes use of a threeelement tube and a network at each station for identifying substations. on aparty line. arrangement is such that a control electrode in the tube at such station is connected to a specially tuned network to bothconductors of the line. Another electrode is connected to ground while a third electrode is connected directly to one of the conductors of the line. At the central omce an arrangement is provided whereby a series of different testing frequencies may be applied in succession across the line conductors and simultaneously current from a special source is applied to the conductor connected directly to the third electrode. In response to a particular frequency applied the network at the calling station causes the associated tube to ionize over the control gap between the first and third elecrodes. This permits current to flow from the special source over the associated conductor and the main gap between the second and third electrodes to ground. This current causes the operation of a relay at the central ofiice to identify the calling'line as determined by the particular testing frequency applied at the time.

- It is a feature of the present invention to employ cold cathode three-element tubes arranged with suitable networks and ground connections at the substations of party lines for identification. If a four-party line is considered, two of the stations are provided with networks so connected and adjusted in relation to the elements of the tubes and the ground that said tubes will ionize in response to low voltage as applied by an alternating current source and one of the tubes will cause rectified current to flow from, said source through it and the line in one direction and the other tube will cause rectified current to This flow from said source through it and the line in the opposite direction, while the networks, tubes and groundconnections atthe other stations are so adjusted and connected that said tubes will only ionize in response to high voltage as applied by an alternating current source and one of these last-mentioned tubes will cause rectified current of one polarity to flow from said source through the tube and the line while the other of this last-mentioned'pair of tubes will cause rectified-current of the-opposite polarity to flow from said source through it in the line.

Another feature is an arrangement at the central office whereby when a test is to be made for a callingsubscriber, the low and high voltages are applied from alternating current sources at the central ofi'ice to the-line in sequence so that one or th other of said voltages will ionize the tube at the calling station and cause the rectified current to flow through the tube and the line'in one direction or the other, and equipment whereby the called line is identified by the application of alternating current voltage of low or high potential and by the flow of the rectified current in one direction or the other. Two polarized relays are arranged in circuits to operate depending on the direction of the rectified current flowing through the line and other relays are provided in the circuits in certain connections to operate to apply the alternating current voltages of the low or high potentials in sequence. Identifying signals or registers may be operated by these relay equipments to identify the calling party.

Another feature relates to means whereby when a test is to be madeas a party is calling, the associated network and tube of the calling station are held connected to the line by the application of current from a direct current source at the central office over the line and the tests may then be performed asdescribed.

This invention has been illustrated in the accompanying drawing in which,

Fig. 1 shows a four-party line and automatic telephone system to which the applicants invention has. been applied; and v Fig. 2 shows a subscribers telephone circuit with a modified equipment in accordance with the applicants invention attached thereto.

Referring now to the drawing the party line i has been shown terminating in four subscribers telephone circuits at A, B, C and D. In the showing for subscriber A, a complete telephone circuit has been shown equipped with a particular circuit arrangement forming part of the equipment for identifying the subscriberjn accordance with the present invention. The equipments for subscribers stations B, C and D have only been shown partially to indicate the special equipments required for identifying the subscribers in accordance with the present invention. The line I may terminate in a line finder 2 whichis merely shown in a diagrammatic form by means of brushes and terminals of a line finder of any type well known in the art. Brushes and terminals for line I have also been shown for extending connections to metering devices for the four subscribers on'line -I. At the central office this .line .finderextends-to an equipment especially providedz-forv identify,

ing calling subscribers and to brushes of. amassociated selector 5 extending to. terminalsfor connections beyond. Any selector circuit well "known in the art may be employed. In this central'.office equipment akey 6 has been shown which may be operatedfto rconnect icertai-n-:1eads to 1 ground to "make the identification equipment effective. .The equipments at"the'-subscribers=stations on .line I"for identifying" arcalling line may, for example, at subscriber-station A consist of a threel elementspacedischarge device l -'I- having its electrodes iconnected e a certain manner through resistances to ground to identify the station. Similardevices 8; 9 and Ill-atstations BQC and D,rrespec.tively; are provided with their electrodes connected in "difierent manners through."resistances tojground' to identify these=stations when calling. To connect these identification equipments at'the subscribers stations, relays are pro 'videdwhich'operate to establish such connections .forstation- A and these relays are marked I I, I2,

I 3 and Mjfor stations A; to D; respectively.

.Referringnow to the operation"oi-this system. it-may be assumed-thatthe subscriber" at station A-callstby removing his receiver from theswitchhook; Thiscloses "a' circuit across the tip and ring conductors and the line finder 2 willoperate to connect the line -I "to the circuit for identifying the'calling station at the central oflice and to the' selector '5 in any well-known manner. When this connection is made circuits -are.completed for the subscriber identifying circuit to opera-te'oneof the-registers of the group I5-to' I8 to -record-that-a calling subscriber has been identified-.- In'this'case the register I5 -will-operateto identify the subscriberat station A when calling. The first operation that takes place. is

the energization of a relay 20 over acircuit from battery through the winding of this relay, contacts ofrelays 2|, 22, and-23 to ground .-at 6. 'ReIay'ZO-in operating connects the subscriber identifying'equipment for testing'to determine which subscriber had called. It'shouldbe noted thatthe-alternating current source 26 is connected through voltage regulator 2-1'and the repeating coil 23to -rectifiers-29- and 30 -for the application of direct current over leads 3| through contacts of relay 20, brushes of line finder 2 over the tip and ring conductors of -line I through the subscribers loop at station A and through the winding of-relay II. Relay II op- --erates-and connectsthe cathode of tube I through its'contacts to the .tip conductor of line' I. -A-circuitis now completed from ground through. a-portion-of the inductance or autotransformer 34; contacts of relay35, windings of relays 36-and '3l' in-.series,=inductance 'I 9 through the rectifierover 'one of the-conductors, contacts-of-relay 20, line finder 2, tip conductor of line I and contacts of relayI I to the cathode-33 This voltageis sufficient to cause .the tube 1 to ionize between the cathode 39 and the control anode 40 through resistance M to ground. The resistance 4| is merely a current limiting device adjusted to cause ionization to take place at this loweryoltage but not to permit appreciable current tofiow. .As tube I ionizes a. rectified current will-.now,ffiow;ithrough this tube from ground 'throughresistance 42, main anode 43, cathode 39 and over the above-mentioned circuit through "the inductance 34 to ground during the negative half .wave of the alternating current as applied through this inductance 34. As the relays 36 and 3 'l are polarized," the: current in the direction from ground' attubeij'l will be. such as to cause the relaytfi-to operate, while relay 31 will not 0perate, being responsive only to current in this circuit in the opposite "direction. Relay 36 in operating-closes a circuit for theoperation -ofrelay 23 from battery through-the lower windingoffthis: relay; contacts of relay 24, contacts of "relay 36,- c0ntacts- 2510f why 32, which is slow in r'eleasing but i releases on f the "operation of relay 20,-: contacts 38: of relay 35, contacts -of relay 22, 4 contacts 442 of irelay -i23, to groundiat 6. -23: in operating 1 closes a 'holding' circuit for' itself from batteryflthrough-its upper winding and Relay upper inner :.arm'ature -and front contact to ,ground at; 6: and. opens the: original circuit for this relay rat .the contacts 44. Relay:23;in.-.operat1'ng cl'oseszra .circuit .for 1 the operation of "regzisteri l ifrombatterythrough the winding of .Jthis xregister,:a terminal and brush of'theline-finder ;-2,;contacts .ofrelay 23 -to ground, thus record- -ing the .iactthat thesubscriber at'station A has -:called.. .R;elay:.23' in. operating also opens the en- -ergizingmircuitafor:relay 20 :so .that' relay 20 will 4 5 ;.now"release'iandlcause the 'rreoperation of relay 32.. .fIhis' :release 1 of relay 20 disconnects the line. from :the' subscriberv identifying equipment ..an'd*iconnects :ittto:the.selector 5 sofithat the -calling :subscriber atstation A may-now dial in .thetusuahmanner to.operate the selector 5 to establish the.connection beyond when dialed itmaytnow bezopened: .to release ;relay 23 'inany 'suitablezmanner, .for' example, by instrumentalities::operative: in: the iselector 5.

4115 the subscriber oflstation B'had called, relay I2 :would; havetoperated towconn'ect tube 8 .to the line '.I; for ionizationribut the lowzvoltage applied at the inductance 34 would:not:..cause this tube to: iOIliZGKOVEITthQ cathodei54s andanode 55, as,

' in radditionf to a resistance T 56" to :ground forthe anode- 55, a: resistance 51 .is inserted across these elements; The tube.8would,- therefore, require a .higher'voltagein order toiionize. This is accomplished .as follows: It should be noted that relay f32xin releasing opens the circuit for 35 which would. release after an: interval due to its :slowto-release characteristics. The release of relay 35Would then close a circuit for the opelation-0f relay 24 from battery through the winding of this relay, contacts 5816f relay 35'to ground..ataaan'd. also open the circuit for'the connection to the inductance. 34 to the lineat contacts 59. Relay 35 would also close a circuit from ground through the inductance 60, contacts 6| of relay 35, windings of relays 36 and 31,

inductance l9, rectifier 29, one of the conductors 3|, "contacts of relay 2!], line finder 2, the tip conductor of line I, contacts of relay I2 to the cathode 54 of tube 8. It should be noted that the inductance 60 is connected in circuit with the alternating current source 26in the same manner as inductance 34 except that inthis case a higher voltage would be applied through the inductance 60 than was applied at inductance 34. This higher voltage will now be sufiicient to ionize the tube 8 across the cathode 54, control anode 55, resistance 56 to ground. As the main anode 62 is connected through a resistance 63 in the same manner as anode 43, for the subscriber at station A, rectified alternating current will now flow through tube 8 in the same direction as for tube 1 and cause relay 36 to operate. When relay 36 now operates, a circuit for relay 64 is closed as soon as the slow-to-release relay 65 releasesdue to the release of relay 35, from battery through the lower winding of relay 64, contact of relays 24, 36, 65, 2|, 22, 23 to ground at 6. Relay 64 in operating closes a locking'circuit for itself from battery through its upper winding, upper inner armature and front contact to ground at 6. This relay now also closes a circuit for the register it from battery through the winding of this register, a terminal and brush of line finder 2, contact of relays 64' and 23 to ground to identify the subscriber at station B as calling. lease relay 2| will release due to the release of relay 65 and cause the release of relay 20 so that the line will be released from the testing equipment and connected to the selector 5.

If the subscriber at station C had called, this station would have been tested by a low voltage applied at the inductance 34 and this low voltage would have been applied through a resistance 66 over the cathode El and anode 68 to ground to ionize tube 9 in the same manner as tube l was ionized. In this case, however, the rectified current through tube 9 will flow in the opposite direction from ground over the anode 68 and main anode 53 through resistance l3, contacts of relay 13, over the line I, line finder 2, contacts of relay 28, one of the conductors 3i, rectifier 29, inductance l9, windings of relays 31 and 36, contacts 59 of relay 35, inductance 3G to ground. As the rectified current is now in the opposite direction, relay 31 will operate instead of relay 36 as in the case of testing for stations A and B and close the circuit for the operation of relay 22 from battery through the lower winding of this relay, contacts of relays 24, 31, 65, 2!, 22 and 23 to ground at 6. Relay 22 in operating closes a looking circuit foritself from battery through itsv upper winding and its inner upper armature and front contact to ground at 6 and also closes a circuit for the register I! from battery through the winding of this register, a terminal andbrush of line finder 2, contacts of relay 22 to ground. Relay 22 in operating causes the release of relay 20 to disconnect the testing equipment from the line and relay 23 reoperates relay 42.

In case the subscriber at station D had called,

the tube ill will not ionize on the low voltage through the inductance 34 as in addition to the resistance 12 for a cathode T3, the control anode M is shunted by a resistance 15, thus requiring a higher voltage to be applied on the cathode l3 Shortly thereafter the sloW-to-re-' beforexthe .tube In ionizes;r..tTherefore .relays 3.2

andt35' are released in succession and the higher through the windingsofrelays 3B and 31, in-

ductance I9, rectifier 29,- one-of the conductors 3!, contacts of relay 2!! through the line finder2 and line i, contacts'of'relay I4, resistance 12, cathode l3, anode M, to ground, to ionize'this tube l3. As relay 35 is released relay 24. will operate. When this-takes place a rectified current is applied in the same direction as rectified current was applied through tube 9, due to the connection of the main anodelfiand resistance 11 to ground through the anode 14 and: relay 31 is then operated from the direct current through tube I'll in'the'proper direction. A circuit is now completedfor relay l9 from battery, lower wind-.

ing ofthis'rel'a'y, contactsof relays 24,- 37, 65,.2l,

22, 23"to" ground at 6. Relay 19 in operating closes a locking circuit" for itself from battery through its upper winding and upper inner armature and front contact to ground at 6, andalso closes the circuit from register-l8 from battery through the winding of this register, a terminal and brushof line finder 2, contacts of relays 19 and 22 to ground to record that the subscriber at station D has called. 'When relay 2|- releases, relay 2B is released and the test 'equipment is disconnected from the line. a v I Thus it-will be seen that in case of a subscriber at station A calling, low voltage will ionize tube land if the subscriber at station B-is calling, a high voltage will ionize -tube8 and in these cases the direction of the rectified current through these tubes 'will'be in the same direction to operatethepolarized relay 36, while'relay' 2 1 will onlyoperate in case'of station B'calling to select the proper register. In case of the station C calling, a low voltage will ioni'ze tube 9 and if the station Dis calling 'a high voltage will ionize tube In, and thedirection of the rectified current through these tubes will be inthe same direction to cause the operation of relay'31 while relay 24 will only operate in case'station D is calling to select the proper register.- Therefore, the testing involves low and high alternating current voltages applied to rectifying tubes and the polarity of the direct current caused by theme In regard to Fig; 2 the subscribers station shown therein has been modified so that inplace of a relay for connecting the tube circuit to one conductor of the party line to identify a calling pa ty, the tube circuit is connected through a pair pr contacts 80' controlled by the switchhook. Thus, when the subscriber removes his receiver from the switchhook the cathode 8| of the tube 32 may be connected to the tip'conductor of the line. In thiscase a direct current supply need not'be provided in the identification equipment at the central oifice and hence the rectifiers 29 and 30 would not berequired.

What is claimed is:

1. In a telephone system, a central office,'a telephone line extending therefrom, two stations on said line, a source of relatively low alternating voltage and a source of relatively high alternating voltage at the central oifice, means for applying said;sources tothe line, means at one station effective when the low voltage source is applied for causing rectified current to fiow in a given direction from said source'over the line, means at the other station efiective when the high voltage'is applied for causing rectified current to fiow in a given direction from said source over the 'lineimznd smeansmesponsi-vettd: ithe crectined'ncur- IBTitiflGWinEifi-ODI SaidiSOUrCES .for. identifyin'gisaid stations; 7 3

2. In F a telephone .'system,-'.'.a I centralt pfliceya :source overzsaidl line in? tone direction;:means at .i-thel'otherroi .rsaidzstations when-calling operative .in' response'ito current from :said direct "current source when" applied to the .line for connecting telephone lineextendin'gtherefrom, .four: stations the'zassociatedl voltage :and current responsive "on? saidz'line, a source of 'ilow' altematin'g. voltage and 1 a "source of high alternating voltage 1 at: said centralioffice', means; for applying: said sourcesrto =said 'lines, means att a setof two of saidstations eilective when the ilow'voltage "source is applied -for: causing -rectifiedrcurrent'to fflow in one direc- I'tion :from: said :source rover the line for one of 'saidxstationsrand intth'e topp'osite direction-for thErIOthi-EI E .of': said Zstation's, means at the other :set' of two r stationsreffectivewheni thehighwoltage source is 5 applied for causing) rectified tcurrenti'to "flow in onexdire'ction from :said is0urce -over said a line for one of said zlast-mentioned stations an'dnin the :opposite direction for the other:zof:said last-'mentionedstations; andz'means responsive to the frectifie'd current fiowing from said sources for identifyingsaid'stations."

'3. In' a telephone system; :a 'line' having four "subscribers stations associated therewith, a source :of low alternating -voltage, eawsource "of liigh' 'alternating voltage, means for applying saidsour'cesto' said 'IlI'IGSyfl-COldCdthOdt-Z tube ateach stationya network and a ground connection associated with each of-said tubes; said network and ground connection at two *of 'said station's being connected to-the corresponding tubes and so adjusted as to cause the associated tubes 'to ionize on the application of"l0w*--a-1ternating voltage to saidilinewhile'one of the tubes causes rectified currentfrom said source to flowthrough the'tube and over the line 1 in-"one direction-rand the -other :tube causes v the rectified current -from'wsaid-source -to 'fiowthroughsaid "other tube and over said" line-in the opposite directionwhen-"saidtubes 'ionize, while the network and 3 ground connections at the other two stations are ="so connected' -with the' corresponding tubes and-so adjustedas :to cause the associated tubes to w i'onize on the 'application-vof ---high alternating voltage through" said =lineand with one of said latter tubes causing "rectified current from said last-mentioned source to flow through said tube overithe line in one: direction and-the other of said last-mentioned -tubesucausing rectified current to.flowfromsaid last-mentioned source through :saidtuberand overthe line the opposite direction- "when I said- I tubes ionize, and means for "identifying :thecalling station operative as "determined sbythe corresponding efiective alternating voltage appliedandlthe direction of :th'erectified currentiiowing through-the line. "4.-In a'-telephone-system,--a central -oifi'ce, a telephone -line,-two stations on said line, a source of' direct current-at-thacentraldfiice, two sources -ofsalternating current of low and high "voltage respectively at the central uofllce, voltage. and current responsive means at each station-,1 means at the central office operative v.when astation is calling for applying-currentirom said direct current source and- -voltageefrom said low and -high alternating ivoltage sources over said line in succession, means at-onei ofsaid stations when calling operative in responsive to current from said direct current-source whenapplied .tothe line for connectingthe-associated 'voltage and current responsive means to said 1 line, said voltage and current responsive means at said-rstation being' then 'responsivewto low alternating voltage applied: atthe central ofiicelforlcausing. rectified current to flow from said'i-low alternating voltage m'eans to saidi'line; saidvoltage and current responsive meansiatrsaid other station being then responsive :to high :alternating voltage 'applied at; the central oflice for causing rectified current -to1flow from said high alternating :voltage 'source 'in "the!oppositedirection, and means at'the centrahofii'ce responsiveto said rectified currents received over said: line to .identify a calling station. a

5. -In,.'a telephone -,system,-a central ofifice, a telephone line, two stations onsaidline, 'a: source of .directcurrent" at the central ofiice, two sources of alternating current of low-and high voltage respectively at the :central office, voltage-and current responsive means at each station, means at the -centralofiice operative when a station is calling for applying current from said direct current-sourceand voltage from said low and high alternating --voltage sources-through said linein succession, means at 'one' of-said stations whencalling operative in response to "current from -saidrdirect current-source when applied to the line for'connect-ing the associated voltage and current-responsive means-tosaid line, said voltage and currentresponsive means [at said station beingthenresponsive to low alternating voltage applied at .the central office for causing :rectified'current to flow from said low alternating voltage source over said line inone direcltionpmeans at the other of said stations when calling operative in response to current from said direct currentsource when applied to the line-for 'connectingthe associated voltage and current-responsive means to said line, said voltage andv current responsive means at said other station-being-then responsive tohigh alternating voltage applied at the central cfiice forcausing rectified current to flow from said high alternating voltage source in the opposite direction, two-oppositely polarized relays at the central oifice, means for operating one of said polarized relays in response to the rectified current applied to the line if said first-mentioned station is-calling and for operating the other of said polarized.relays in response to the-rectified current applied-to the line if saidsecond-mentioned station is calling, means responsive to the operation of said first-mentioned relay for identifying said. first-mentioned calling station, and .means responsive to the operation of said secondment-ioned relay for identifying said last-mentioned calling station.

6. In a telephone system, a central office, a telephone line extending therefrom, four sta- V tions on said'line, a source .of-relatively low alternating voltage and a-source of relatively high alternating voltage atsaid central.-office,. means forapplyingsaid sourcesrto said line operative when a station is calling, means at two of said stationseffectivewhenthelow voltage source is applied for causing rectified current ofrone direction or the other to flow over said line to said central office from said low voltage source depending on whether one vor the otherv of said stations is calling, means at said two other stations effective when the high voltage source is applied for causing rectified current of one direc tion or the other to flow over saidline to said central oflice fromsaid'high voltage source depending on whether .one or the other of said last-mentioned stations is calling, and means at said central ofiioe responsive to a rectified current flowing from said low voltage source over said line for identifying one or the other of said first-mentioned stations if calling and depending on the direction of the rectified current flowing, and responsive to rectified current flowing from said high voltage source over said line for identifying one or the other of said lastmentioned stations if calling and depending on the direction of said rectified current.

7. In a telephone system, a central office, a telephone line extending therefrom, four stations on said line, a source of relatively low a1- ternating voltage and a source of high alternating voltage at said central oflice, means at one of two stations operative when calling for applying the low voltage source to said line and responsive to the application of said low voltage source for causing rectified current to flow in one direction from said source over said line, means at the other of said two stations when calling for applying the low voltage source to said line and responsive to the application of said low voltage source for causing rectified current to flow in the opposite direction from said source over said line, means at said central office and at one of the other two stations operative when calling for applying said high voltage source to said line and responsive to the application of said high voltage source for causing rectified current to flow in one direction from said source over said line, means at the central oflice and at the other of said last-mentioned two stations operative when calling for applying said high voltage source to said line and responsive to the application of said high voltagesource for causing rectified current to flow in the opposite direction from said source 'over said line, and means at the central office responsive to a rectified current flowing over said line in one direc tion or the other and depending on whether the low voltage or the high voltage source was applied to the line for identifying a corresponding calling station.

MASON A. LOGAN. 

